Using React in Visual Studio Code

We’ll be using the for this tutorial. To use the generator as well as run the React application server, you’ll need Node.js JavaScript runtime and (Node.js package manager) installed. npm is included with Node.js which you can download and install from Node.js downloads.

You can now create a new React application by typing:

where my-app is the name of the folder for your application. This may take a few minutes to create the React application and install its dependencies.

Let’s quickly run our React application by navigating to the new folder and typing npm start to start the web server and open the application in a browser:

cd my-app
npm start

You should see the React logo and a link to “Learn React” on in your browser. We’ll leave the web server running while we look at the application with VS Code.

To open your React application in VS Code, open another terminal or command prompt window, navigate to the my-app folder and type code .:

In the File Explorer, one file you’ll see is the application README.md Markdown file. This has lots of great information about the application and React in general. A nice way to review the README is by using the VS Code Markdown Preview. You can open the preview in either the current editor group (Markdown: Open Preview kb(markdown.showPreview)) or in a new editor group to the side (Markdown: Open Preview to the Side kb(markdown.showPreviewToSide)). You’ll get nice formatting, hyperlink navigation to headers, and syntax highlighting in code blocks.

Syntax highlighting and bracket matching

Now expand the src folder and select the index.js file. You’ll notice that VS Code has syntax highlighting for the various source code elements and, if you put the cursor on a parenthesis, the matching bracket is also selected.

IntelliSense

As you start typing in index.js, you’ll see smart suggestions or completions.

After you select a suggestion and type ., you see the types and methods on the object through IntelliSense.

VS Code uses the TypeScript language service for its JavaScript code intelligence and it has a feature called Automatic Type Acquisition (ATA). ATA pulls down the npm Type Declaration files (*.d.ts) for the npm modules referenced in the package.json.

If you select a method, you’ll also get parameter help:

Go to Definition, Peek definition

Through the TypeScript language service, VS Code can also provide type definition information in the editor through Go to Definition (kb(editor.action.revealDefinition)) or Peek Definition (kb(editor.action.peekDefinition)). Put the cursor over the , right click and select Peek Definition. A will open showing the App definition from App.js.

Press kbstyle(Escape) to close the Peek window.

Hello World!

Let’s update the sample application to “Hello World!”. Add the link to declare a new H1 header and replace the <App /> tag in ReactDOM.render with element.

import React from 'react';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
var element = React.createElement('h1', { className: 'greeting' }, 'Hello, world!');
ReactDOM.render(element, document.getElementById('root'));
serviceWorker.unregister();

Once you save the index.js file, the running instance of the server will update the web page and you’ll see “Hello World!”.

To debug the client side React code, we’ll need to install the Debugger for Chrome extension.

Open the Extensions view (kb(workbench.view.extensions)) and type ‘chrome’ in the search box. You’ll see several extensions which reference Chrome.

Press the Install button for Debugger for Chrome.

To set a breakpoint in index.js, click on the gutter to the left of the line numbers. This will set a breakpoint which will be visible as a red circle.

Configure the Chrome debugger

We need to initially configure the debugger. To do so, go to the Run view (kb(workbench.view.debug)) and click create a launch.json file to customize Run and Debug. Choose Chrome from the Select Environment drop-down list. This will create a launch.json file in a new .vscode folder in your project which includes a configuration to launch the website.

We need to make one change for our example: change the port of the from 8080 to 3000. Your launch.json should look like this:

Ensure that your development server is running (npm start). Then press kb(workbench.action.debug.start) or the green arrow to launch the debugger and open a new browser instance. The source code where the breakpoint is set runs on startup before the debugger was attached, so we won’t hit the breakpoint until we refresh the web page. Refresh the page and you should hit your breakpoint.

You can step through your source code (kb(workbench.action.debug.stepOver)), inspect variables such as element, and see the call stack of the client side React application.

The Debugger for Chrome extension README has lots of information on other configurations, working with sourcemaps, and troubleshooting. You can review it directly within VS Code from the Extensions view by clicking on the extension item and opening the Details view.

Live editing and debugging

If you are using together with your React app, you can have a more efficient workflow by taking advantage of webpack’s HMR mechanism which enables you to have live editing and debugging directly from VS Code. You can learn more in this Live edit and debug your React apps directly from VS Code blog post and the .

Linting

Try making a small error in your React source code and you’ll see a red squiggle and an error in the Problems panel.

Linters can provide more sophisticated analysis, enforcing coding conventions and detecting anti-patterns. A popular JavaScript linter is ESLint. ESLint, when combined with the ESLint VS Code , provides a great in-product linting experience.

First, install the ESLint command-line tool:

npm install -g eslint

Then install the ESLint extension by going to the Extensions view and typing ‘eslint’.

Once the ESLint extension is installed and VS Code reloaded, you’ll want to create an ESLint configuration file, .eslintrc.js. You can create one using the extension’s ESLint: Create ESLint configuration command from the Command Palette (kb(workbench.action.showCommands)).

The command will prompt you to answer a series of questions in the Terminal panel. Take the defaults, and it will create a .eslintrc.js file in your project root that looks something like this:

ESLint will now analyze open files and shows a warning in index.js about ‘App’ being defined but never used.

You can modify the ESLint in the .eslintrc.js file.

Let’s add an error rule for extra semi-colons:

 "rules": {
        "no-extra-semi":"error"

Now when you mistakenly have multiple semicolons on a line, you’ll see an error (red squiggle) in the editor and error entry in the Problems panel.

In this tutorial, we used the create-react-app generator to create a simple React application. There are lots of great samples and starter kits available to help build your first React application.

VS Code React Sample

This is a sample React application used for a at the 2016 //Build conference. The sample creates a simple TODO application and includes the source code for a Node.js Express server. It also shows how to use the ES6 transpiler and then use webpack to bundle the site assets.

There is helpful VS Code-specific documentation at which details setting up Node.js server debugging. VS Code also has great MongoDB support through the extension.

TypeScript React

If you’re curious about TypeScript and React, you can also create a TypeScript version of the create-react-app application. See the details at on the TypeScript Quick Start site.

Angular

Angular is another popular web framework. If you’d like to see an example of Angular working with VS Code, check out the recipe. It will walk you through creating an Angular application and configuring the launch.json file for the Debugger for Chrome extension.

Common questions

Can I get IntelliSense within declarative JSX?

Yes. For example, if you open the create-react-app project’s App.js file, you can see IntelliSense within the React JSX in the method.